1. Field of the Invention
This invention relates to oral care compositions, and, more particularly, to a polymer for use in such compositions which has a reactive group therein covalently bonded to an active material, such as a bactericide, flavorant and/or essential oil compound, which bond is readily hydrolyzable in the aqueous condition of the mouth of the user to release the material therein.
2. Description of the Prior Art
Oral care compositions such as dentifrices, denture adhesives, buccal tapes, anti-plaques, mouthwashes, mouthstrips, and chewing gums usually contain one or more added active materials, particularly antimicrobial compounds, e.g. triclosan or thymol, or flavorants, e.g. menthol and thymol, or essential oils. However, these active materials are released immediately after use into the mouth of the user, and, accordingly, are not available at any time thereafter.
On the other hand, the related U.S. Pat. Nos. 6,315,987 and 6,464,961 described a copolymer of maleic anhydride and methyl vinyl ether having e.g. an active menthol group covalently bonded by esterification to the reactive anhydride of the copolymer, which ester group only slowly hydrolyzed in aqueous solution, and thus very little of the active was released at the instant of use.
For these reasons, it is an object of this invention to provide an oral care composition including a polymer which is a delivery system which can release a proportion of the active compound when the polymer is present in the aqueous condition of the mouth, with the rest of the polymer being made available for hydrolysis thereafter.
Another object of the invention is to provide such an oral care composition in which the polymer also is bioadhesive to the teeth and gums of the user.
These and other objects and features of the invention are achieved herein by the provision of a polymer for use in an oral care composition which includes a monomer repeat unit containing an active material covalently bonded to a hydrolyzable side group of the monomer unit, and a spacer group positioned between the main chain of said polymer and the hydrolyzable side group, the polymer having a predetermined rapid rate of aqueous hydrolysis to release the active material therefrom.